Collapsible motor operated antenna

ABSTRACT

A retractable motor-driven antenna 10 of compact size and light weight capable of being supported at the top of a support tube 14. A molded plastic housing 12, 30 in part forms the drive motor. A drive transmission 34 for extending and retracting the antenna mast 15 uses a timing belt 78 and pulley wheels 61, 62 and includes an overrunning clutch 84 or energy storage and release interconnection 76 between a drive pulley wheel 261 and a motor output shaft that drives a flexible cord 46 connected to the antenna mast. A switch assembly within the housing includes automatically stops the drive when the mast reaches its extended or retracted position or is obstructed. A coupling between the molded plastic housing and an antenna support tube isolates the housing from road vibration.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. application Ser. No.563,402, filed Dec. 7, 1983, entitled "Collapsible Motor-operatedAntenna" which is a continuation-in-part of U.S. application Ser. No.366,918, filed April 9, 1982, entitled "Collapsible Motor-operatedAntenna", both abandoned.

TECHNICAL FIELD

This invention relates to a collapsible, motor-operated, (so-called"electric") antenna, especially for automotive use.

BACKGROUND ART

Collapsible antennas raised and lowered by electric motors are widelyused on automobiles. Such antennas are typically mounted in a fenderwell. The power and strength required for the drive mechanism has, inthe past, required a relatively bulky and heavy antenna and motorassembly, requiring substantial space and a relatively strong mountingbracket within the fender well. With the present popularity of smallerand lighter automobiles, the available space for automotive accessoriesis at a premium. The space used by one accessory takes from thatavailable for another. In addition, the weight of an automobile has asubstantial effect upon its gasoline mileage and substantial effort isbeing made to reduce the total weight of automobiles. Accordingly, theneed for compact and lightweight accessories, including motor-operatedantennas, is especially great. Nevertheless, a motor-operated antennamust be rugged and powerful enough to function under the adverseconditions of vibration, snow, ice, and the like, and be low in cost andreliable in its operation.

DISCLOSURE OF INVENTION

The present invention overcomes the size and weight disadvantages ofknown motor-operated antennas by providing a small, light-weight,rugged, motor-operated, collapsible antenna that is relatively low incost. The antenna is small enough and light enough to be mounted with aminimum of bracketing. It is of a size that permits it to be mounted ina space 3 inches by 11/2 inches by 13 inches. In a preferred embodiment,the antenna weighs approximately one pound and can be satisfactorlymounted with top hardware only. This eliminates a redundant groundconnection and support.

The disclosed motor driven antenna includes a supporting tube and anumber of telescoping antenna sections collapsible within the tube. Areversible electric motor extends and retracts the antenna sections viaa transmission having a rotatably supported nut that engages threadedportions of a flexible cord connected at one end to one of the antennasections.

A compact, light-weight, drive transmission is provided by two pulleywheels and a belt that establish a substantial speed reduction and henceallow use of a relatively small DC reversible electric motor to supplythe necessary power to raise and lower the antenna sections. One pulleywheel drives the rotary nut, which is journalled in the housing. The nutdrives the threaded cord connected to the antenna sections and extendingthrough the housing. An interconnection is provided for absorbing,storing and releasing rotary energy. The interconnection preferablyincorporates an overrunning slip clutch. The arrangement serves as aprogressive braking means at the end of antenna travel and then, afterdecelerating the rotating members to a stationary condition, unwinds torelieve forces on the system elements. The arrangement also allows thedrive motor to continue running a short time after antenna movementstops, without overloading the motor. This provides for a "soft start"in either direction, requiring less starting torque from the motor.

Motor energization and direction of rotation is controlled by a relayactivated by a radio on/off switch. The motor is de-energized by a limitswitch that responds to antenna movement and senses when the rotary nuthas driven the antenna to a limit of travel. When a travel limit isreached, the switch senses movement of a flange coupled to the drive nutand deenergizes the motor. In this preferred embodiment a spring biasedthrust bearing allows a driven pulley to move up and down within thebearing when a travel limit is reached.

In an alternate embodiment, the motor is deenergized by a transducermounted in close proximity to the nut that drives the antenna sections.The transducer senses rotation of the nut and once rotation stops,indicating the antenna is either fully retracted or extended, thetransducer disrupts power to the motor.

The preferred transducer is a Hall-effect transducer which generates aseries or sequence of pulses as the nut rotates. These pulses maintain abipolar switch coupled to the motor in a conductive state. When thepulses stop the switch is rendered nonconductive and power to the motoris disrupted. The motor is disabled regardless of the reason rotationstops so that if, for example, the antenna cannot be extended orretracted to its full extent, the motor is not overloaded.

An improved housing is provided to in part comprise the drive motor, andto enclose a motor switch and drive transmission, and to connect withone end of a supporting tube that receives the telescoping antennasections. The motor is supported beside the supporting tube, with itsshaft parallel to the tube. In the preferred embodiment, the housing isa multiple piece housing of molded plastic. Two of the pieces form acavity to house the drive transmission and switch, and provide a throughpassage centrally of a boss that connects with the antenna sections andsupporting tube. A threaded drive cord that extends and retracts theantenna sections passes through the passage. A third piece of thehousing extends beside the boss and supporting tube from the chamberformed by the other two pieces, and houses the motor armature. The twopieces of the housing forming the chamber are of the same width as thethird housing piece and the construction provides a very narrowassembly.

A flexible coupling between the housing and the antenna support tubeisolate the housing from road vibration. A tubular neoprene rubberconnector is coupled to a housing boss at one end and to the supporttube at an oposite end so that vibrations are absorbed by the connectorbefore they reach the plastic housing.

The above and other features and advantages of the invention will becomemore apparent from the detailed description that follows, whenconsidered in connection with the accompanied drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side elevational view of an antenna assembly embodying thepresent invention;

FIG. 2 is an end elevational view of the antenna of FIG. 1;

FIG. 3 is a partial sectional view of the antenna of FIGS. 1 and 2,taken along the line 3--3;

FIG. 4 is a schematic diagram of a control circuit for operating themotor of the antenna shown in FIGS. 1-3;

FIG. 5 is a schematic of an alternate and preferred control circuit foroperating the motor;

FIG. 6 is a partial sectional view of the antenna of FIGS. 1 and 2showing the antenna supported by a mounting surface;

FIG. 6A is an enlarged sectional view showing details of a retainingcollar which can be removed to allow a replaceable antenna unit to bereplaced;

FIG. 7 is a partial sectional view of an antenna drive showing detailsof the construction of that drive;

FIG. 8 is a sectional view taken along the line 8--8 of FIG. 7;

FIG. 9 is a sectional view showing a bottom of the antenna coupled to aplastic insulator sleeve which defines a passageway through which waterflows away from the antenna drive to an exterior of the antennaassembly;

FIG. 10 is a sectional view of an alternate embodiment of the antenna;

FIG. 11 is a sectional view showing the modified embodiment having aclutch engagement;

FIG. 12 is a sectional view taken along the line 12--12 of FIG. 10;

FIG. 13 is a sectional view of an alternate and preferred embodiment ofthe antenna; and

FIGS. 14 and 15 are end elevational views of the FIG. 13 embodiment ofthe antenna.

BEST MODE FOR CARRYING OUT THE INVENTION

An antenna assembly 10 embodying the invention is shown in FIGS. 1-3,comprising a housing 12 for a motor and drive transmission, a supportingtube 14 for supporting the assembly and for housing a collapsibleantenna mast 15 comprised of telescoping sections 16, and a flexiblesotrage tube 22 for a flexible cord that extends and retracts thetelescoping sections 16a-d. As FIGS. 1 and 2 show, the housing 12 iselongated and very little wider than the supporting tube 14. Theassembly is very compact and can be mounted within a small space.

As best shown in FIG. 3, the housing 12 is formed of three injectionmolded plastic pieces 26, 28, 30, that interfit to form a strongenclosure. Pieces 26, 28 together form a cavity 31 for a printed circuitboard and switch assembly 32 and a drive transmission 34. The housingpiece 26 has a cylindrical boss 36 projecting perpendicularly from a topwall 38 to connect with the supporting tube 14. The housing piece 28 hasa cylindrical boss 40 extending perpendicular to a bottom wall 41,aligned with the boss 36, and accommodating connection of the flexiblestorage tube 22 with the housing.

A central opening 42 extends through the boss 36 and a central opening44 extends through the boss 40, each axially aligned with the other, toaccommodate passage of a flexible cord 46 through the housing. Beyondthe boss 36, the cord is connected to a center antenna section 16a by acoupling tube 43 which is crimped about the cord 46 and center section16a. Beyond the boss 40, the cord 46 extends into the storage tube 22.

The cord is of plastic, such as Delrin, and is externally threaded ontwo diametrically opposite portions. The cord has two diametricallyopposite flat outer surfaces 46a, 46b along its length, resulting inperipherally broken threads. The cord passes through a central opening48 of a tubular plastic insulator 45 within the boss 36, the insulatorbeing cylindrical and slidably received within a cylindrical wall 47within the boss 36. The insulator is partially received within the baseof the fixed tube 16e and the two are secured together, as by crimpingor otherwise, deforming a part of the tube into the insulator. Twoopposed flat surfaces 48a, 48b of the plastic insulator prevent rotationof the cord 46 relative to the housing, yet provide sufficient clearanceto allow free sliding of the cord. Because the inside passage 48 issubject to wear from the movement of the cord 46 it is made longrelative to its diameter (several times as long) and is replaceablewithin the housing.

To avoid risk of malfunctioning of the antenna drive from exposure towater that may find its way into the housing along or near the antennamast, and which in cold weather can freeze and prevent relative movementbetween parts of the tubular drive transmission, two passages 49 (FIG.9) are provided in the boss 36. The passages open at one end 49a incommunication with drains 45a, 45b in the tubular insulator 45 and atthe other end 49b at the exterior of the housing below the supportingtube 14, and are inclined downwardly and outwardly. The drains 45a, 45bare located above an O-ring seal 53 at the base of the insulator 45,between the insulator and the housing wall 38. Water leaking along theantenna 15 mast is intercepted before reaching the seal 53 and carriedaway through the less restrictive drains 45a, 45b and passages 49 to theoutside of the housing. Also, water that may find its way between thetelescoping antenna sections will tend to be flung from the cord 46 asit is rotated and will be received by the drains 45a, 45b. The seal 53blocks the flow of any water that might happen to seep past the drains45a, 45b.

An upper end of the support tube 14 is securely fastened by brazing orwelding to a metal mounting member 54, which extends through an openingin a mounting sheet 55 such as an automobile fender or the like (FIG.6). Top 57a and bottom 57b mounting brackets orient the antenna sections16a-e at any desired angle with respect to the sheet 55 so that theantenna rises in the desired direction when it is extended.

A tubular plastic insulator 63 fits closely around the upper end of theouter fixed antenna tube 16d and includes a circular external shoulder63a, which rests against an upper end of the mounting member 54. Withthe insulator 63 in place, a retaining nut 65 having an inner threadedportion is tightened down over an outer threaded portion of the mountingmember 54 until the brackets 57a, 57b and mounting member 54 aresecurely mounted to the sheet 55.

The antenna sections 16a-d are replaceable so that if any are broken orbent an entire unit of those sections 16a-d may be removed and replaced.The outer section 16d is retained within the fixed antenna tube 16e by aretaining collar 67 that has a central opening 67a closely surroundingthe section 16d which is too small to allow the enlarged base portion16d (FIG. 3) to pass through. The collar 67 has an internal thread 67bthat engages a threaded exterior portion 16ea at the extending end ofthe fixed antenna tube 16e. When the collar 67 is securely fastened tothe outer tube 16e, a reduced diameter portion 67c telescopes into acylindrical recess 69 formed between the end of the outer tube 16e andthe insulator 63. A circumferential flange 67d abuts the end of theinsulator 63.

The housing piece 26 (FIG. 3) has an opening 50 in the top wall 38, inwhich a spherical bearing 51 is located that rotationally supports anarmature shaft 52 of a motor 60 along an axis that is parallel to thelongitudinal extent of the antenna mast 15.

The housing piece 30 is a generally cylindrical, cup-like, member thatcarries a spherical bearing 56 at an upper end, in which the armatureshaft 52 is journalled. It also carries permanent motor field magnets 58which are bounded by an iron shield 58a that protects the magnets 58from exposure to extremely low temperatures which can reduce theintensity of the magnetic field they create.

The drive transmission 34 has a drive pulley 61 in the cavity 31,secured to the end of the motor shaft 52, which extends through the topwall 38 into the cavity 31. A driven pulley 62 is supported laterally toone side of the drive pulley 61, between two bearings 72, 74. Thebearing 72 is secured in the housing piece 26 and the bearing 74 in thehousing piece 28, each adjacent a respective boss 36, 40, mounting thepulley 62 in axial alignment with the central openings 42, 44 thattogether form a through passage.

The driven pulley 62 is of a two piece construction. A hub portion 64(FIGS. 3 and 7) has top and bottom flanges 66a, 66b that rotatablysupport a sleeve 68 having gear teeth about its periphery. The hub 64has a central through passage with internal threads 70 that engage thethreads of the cord 46 and acts as a rotary nut to drive the cord. Atiming belt 78 driven by the pulley 61 engages the teeth on the sleeve68 which rotates the hub 64 through an overrunning clutch 84. The clutch84 is interposed between the sleeve 68 and hub 64 so that rotation fromthe sleeve to the hub is transmitted through the clutch 84.

The threaded relationship of the hub 64 and the cord 46 results in thelongitudinal movement of the cord 46 upon rotation of the hub 64, whichis restrained from axial movement by the bearings 72, 74. Thus, rotationof the hub through the transmission 34 drives the cord in a direction toextend the antenna sections or retract them, depending upon thedirection of motor rotation. Because the pulley 61 is substantiallysmaller in diameter than the pulley 62, a speed reduction and powerincrease result.

As best shown in FIG. 7, the flange 66b is integral with the hub 64. Theflange 66a is keyed to the hub and secured to the flange 66b byextensions 66c that extend into holes in the flange 66b and are heatwelded in place.

The clutch 84 automatically decreases the force by which the hub andsleeve are interengaged when the antenna reaches the end of its travelduring extension or retraction. The clutch overruns smoothly and withoutgeneration of excessive heat. This is accomplished by the use of aspring strip wrapped in a ring-like shape within an inside cylindricalsurface 86 of the sleeve 68. The resilience of the spring strip causesit to engage the inside cylindrical surface 86 with sufficient force tofrictionally rotate with the driven pulley under the loads experiencedduring extending and retracting the antenna sections when the sectionsare not obstructed.

The spring strip encircles the hub 64 and has an inturned flange at 84a,84b at each opposite end, received in a notch 88 in the hub 64. Thenotch is sufficiently large circumferentially to allow some peripheralmovement of the ends of the spring, which are spaced from each otherperipherally a short distance, as best illustrated in FIG. 8. Asillustrated in FIGS. 7 and 8, the spring surrounds the outside diameterof the adjacent nut portion with radial clearance. Rotation of thesleeve, transmitted to the spring through friction, causes rotation ofthe hub by contact of one of the flanges 84a, 84b of the spring with anend of the receiving notch 88.

When rotation of the hub is stopped, as at the end of antenna travel,the frictional force of the sleeve 68 on the spring causes the spring torotate slightly. This moves a free end of the spring toward the oppositeend, reducing the diameter of the spring and relieving the frictionalforce against the inside diameter of the sleeve. This allows the sleeveto be rotated more freely by reduction of the frictional force betweenthe spring and pulley, and thereby reduces the load on the motor and thegeneration of heat through the relative sliding. As will be apparentfrom FIG. 8, the spring functions identically in either direction ofrotation of the driven pulley.

As shown in FIG. 3, the upper boss 36 receives the supporting tube 14 inclosely surrounding relation. The mast is secured to and supported bythe insulator 45, which compresses the O-ring seal 53. Duringinstallation of the antenna, the mast 15 and attached cord 46 isinserted into the tube 14 so the cord 46 can be inserted into theopening in the hub 64. When the mast 15 is inserted, the insulator 45 isoriented so its drains 45a, 45b communicate with the passageways 49(FIG. 9) which, in a preferred embodiment, leads away from the threadson the cord 46 to the exterior of the housing 26. The motor 60 isenergized in a direction to draw the cord 46 into the hub 64 until themast approaches the position shown in FIG. 3, i.e. where the retainingnut 67 screwed to the outer mast section 16e begins to seat in therecess 69 in the top insulator 63 (FIG. 6). At this time a bottom end ofthe insulator 45 begins to compress or at least contact the O-ring seal53.

The mast 15 is inserted a slight distance further until the collar 67completely seats in the recess 69, with the flange 67d abutting the endof the insulator 63. This additional movement is accomplished bycompressing the O-ring seal between the insulator 45 and a restrictedregion 71 of the housing member 26 through which the hub portion of thedriven pulley 62 fits. Once the mast is properly seated in place,threaded connectors 73 with pointed ends are screwed through the tube 14and boss 36, into the insulator 45 securely positioning the mast 15 inplace. In a preferred embodiment three connectors 73 are used. In theevent of damage to the core sections 16a-d those sections may bereplaced as outlined above without removing the outermost section 16ewhich is fastened to the insulator 45.

The storage tube 22 for housing the cord 46 fits inside the boss 40. Thetube has a shoulder 82 on the end to retain it within the housing. Thestorage tube 22, being flexible, can be bent to whatever contourdesired, depending upon the wheel well shape and construction in whichthe assembly is mounted, to provide an enclosure for the cord 46 whenthe antenna mast is collapsed. Alternatively, it can be preformed to adesired contour.

A schematic wiring diagram of the switch assembly 32 located within thehousing piece 28 is shown in FIG. 4. As shown, power from a battery suchas an automobile battery is supplied to the DC motor 60 through lines90, 91. The direction of the motor is controlled by the polarity of thecurrent applied through the leads, which can be changed through a doublepole, double throw, center off toggle switch SW1 mounted to anautomobile dashboard.

A switching circuit 89 is interposed in the lead 91 by two connectingleads 93, 94. Both leads 93, 94 connect to a rectifying bridge typecircuit 96 from which two lines 98, 99 of the switching circuit areconnected. The bridge circuit 96 maintains a first junction 95 negativeand a second junction 97 positive regardless of the polarity of theswitch SW1 to allow the switching circuit to operate regardless of achange of polarity at the connections 93, 94 when current to the motor60 is reversed.

The switch circuit 89 removes the power from the motor when a presettime and current load conditions have been met, such as a short timeafter the motor reaches the end of its travel and a greatly increasedload and hence current demand is placed upon the motor 60.

The circuit 89 of FIG. 4 includes diodes CR1, CR2, CR3 and CR4, threetransistor Q1, Q2 and Q3, a capacitor C1 and resistors R1=1k, R2=10k,R3=10k, R4=10k, R5=1k and R6=1 ohm, all connected as shown to conductcurrent to the motor 60 until a predetermined current load is appliedfor a predetermined time.

When the switch SW1 first couples the battery to the motor 60 to drivethe antenna up or down the NPN power transistor Q3 conducts in asaturated state so the car battery drives the motor 60 through the 1 ohmresistor R6. Q1 is turned off since the voltage across the one ohmresistor R6 is too small to bias that transistor into conduction. Whenthe motor experiences a greater load as it drives the antenna to an endof travel, the current through the motor will increase causing thevoltage across the resistor R6 to rise to the point where the transistorQ1 turns on. This turn on causes the capacitor C1 to charge with a R2C1time constant until Q2 turns on. When the transistor Q2 turns on thebase voltage on Q3 drops turning Q3 off. The automobile battery nowdrives the motor 60 through the 1k resistor R5 instead of the 1 ohmresistor R6. The current through the motor 60 drops to a point where themotor no longer rotates. This state continues until the user toggles theswitch SW1 back to its center off position.

As an alternative embodiment, a magnet 98 is located in the flange 66badjacent a Hall-effect transducer 99 and associated circuitry 100 thatreplaces the switch circuit 89. The Hall-effect switch senses rotationof the magnet 98 which rotates in excess of 20 revolutions per secondwhen the motor is extending or retracting the antenna.

Two inputs M1, M2 to the circuit 100 (FIG. 5) are motor inputs whichdrive the motor in one of two directions depending upon the polarity oftwo inputs IP-1, IP-2 from a switch SW2. The switch SW2 is a doublethrow, double pole switch whose polarity is controlled by a relay (notshown) having a holding coil energized through the radio. When the coilis de-energized the switch polarity retracts the antenna and when thecoil is energized the polarity is switched to extend the antenna. Thus,the antenna will extend automatically whenever the ignition and radioare both activated and will retract when either the radio or theignition is switched off. In this embodiment the motor 60 is alsoenergized by the car battery (not shown) so the retraction of theantenna is accomplished even though the ignition is switched off.

Assume a positive input at IP-1 which is transmitted through a diode andcapacitor C2 to a base input of an NPN transistor Q-2, turning thattransistor on. This in turn turns on one of the two power transistorsQ-3, Q-4 to the right of FIG. 5. When IP-1 is positive it is seen that adiode between IP-1 and the emitter of Q-3 conducts so that transistorQ-2 turns on power transistor Q-3. Alternately when IP-1 is negative,capacitor C3 turns on Q-2 which turns on Q4 and the direction of currentflow through the motor is reversed. Thus, whenever the transistor Q-2conducts, one or the other of the power transistors Q-3 or Q-4 is biasedinto conduction by a signal at the base of that power transistor so thatthe application of either polarity signal at IP-1 and IP-2 energizes themotor 60.

The signal applied to IP-1 and IP-2 is a DC signal so that after theinitial receipt of that signal the two capacitors C-2 and C-3 will blockthe transmission of those signals to the base of the transistor Q-2.Thus, but for the presence of the Hall-effect transducer 99 and a fourthtransistor Q-1, the motor would receive a signal temporarily and oncethe blocking effect of C-2 and C-3 take effect, motor rotation wouldterminate.

Once rotation of the motor begins, however, the Hall-effect transducer99 senses magnet rotation and generates pulses at its terminal labeled#3 in FIG. 5. These pulses are coupled through a capacitor C-4 and adiode to the base of the transistor Q-2. Periodic receipt of this pulsecontinues to bias transistor Q-2 into conduction which in turn keeps onepower transistor (Q3 or Q4) turned on maintaining the motor drivesignals at M-1 and M-2. In the event the motor drive action moves theantenna to one of its limits of travel, continued movement is no longerpossible and the Hall transducer no longer generates these pulses. Oncethese pulses stop the transistor Q-2 also ceases to conduct since itsbase emitter junction no longer has the necessary voltage across it andfor a similar reason the power transistor (either Q-3 or Q-4) also stopsconducting.

A transistor Q-1 insures that the alternating pulses appearing at thebase of the transistor Q-2 are generated from movement of the antennadrive and not from spurious vibrations in the car fender. The same inputfrom either IP-1 or IP-2 which initially biases transistor Q-2 intoconduction appears at the base of transistor Q-1 to cause conduction inthat transistor. This transistor will continue to conduct untiltransistor Q-2 turns off at which time transistor Q-1 also turns offdisabling the Hall-effect transducer. Thus, the Hall-effect transduceris only capable of transmitting pulses when transistor Q-1 conducts andthis transistor in turn can only conduct when an input appears at eitherIP-1 or IP-2. Once the end of travel has been reached and the transistorQ-1 is turned off, spurious vibrations to the Hall-effect transducerwill never reinitiate conduction in transistor Q-2 without theappearance of the signal at IP-1 or IP-2.

In summary, as long as the antenna is extending or retracting throughhub rotation, either transistor Q-3 or Q-4 conducts; but upon reachingthe end of travel or an obstruction, stopping the hub rotation, theconducting transistor turns off, automatically disrupting power to themotor drive. When the car radio is turned off, the inputs IP-1 and IP-2are reversed to reverse current direction through the motor and theHall-effect transducer generates pulses causing the motor to retract theantenna by driving the hub in the opposite direction until the antennais fully retracted or movement is obstructed.

The circuit 100 (FIG. 5) is preferable to the circuit 89 (FIG. 4) sincethe user need not deactivate the circuit 100 after the motor 60 hasfully extended or retracted the antenna. After the car ignition isturned off, IP-1 and IP-2 are still coupled to the battery by the switchSW2 but when all transistors are turned off the circuit 100 draws onlyabout 3 milliamps, a current the battery can supply for over 3000 hourswithout problem.

The Hall-effect transducer can be replaced with other means forgenerating a pulse train to maintain the transistor Q-2 conductive. Anoptical sensor might be mounted in close proximity to the flange 66b tosense rotation of a mark or irregularity in the flange. The irregularitymight comprise, for example, castellations or slots in the flange 66bwhich would preferably trigger the optical sensor. Such an opticalsensor would include an infrared radiation source which would beinsensitive to dirt build-up in the vicinity of the flange 66b.

An alternate antenna assembly 110 is shown in FIGS. 9-11. The assembly110 includes a housing 112, supporting tube 114, antenna mast 115 andtelescoping antenna sections 116. As best shown in FIG. 9, the housing112 is formed of three injecting molded plastic pieces 126, 128, 130,that interfit to form a strong enclosure. Pieces 126, 128 together forma cavity 131 for a switch assembly 132 shown in phantom and a drivetransmission 134. The housing piece 126 has a cylindrical boss 136projecting perpendicularly from a top wall 138 to connect with asupporting tube 114. The housing piece 128 has a cylindrical boss 40extending perpendicular to a bottom wall 141, aligned with the boss 136,and accommodating connection of a flexible storage tube 122 with thehousing.

A central opening 142 extends through the boss 136 and a central opening144 extends through the boss 140, each axially aligned with the other,to accommodate passage of a flexible cord 146 through the housing.Beyond the boss 136, the cord extends through antenna sections 116, andbeyond the boss 140, it extends into the storage tube 122. The cord isof plastic, such as Delrin, and is externally threaded on twodiametrically opposite portions. The cord has two diametrically oppositeflat outer surfaces 146a, 146b along its length, resulting in brokenthreads. The flat portions are adapted to be engaged by two opposed flatsurfaces 148 of the central opening 142, which prevent rotation of thecord relative to the housing. Sufficient clearance is provided betweenthe cord and the opening 142 to allow free sliding of the cord.

To avoid risk of malfunctioning of the antenna drive from exposure towater that may find its way into the housing along or near the antennamast, and which in cold weather can freeze and prevent relative movementbetween parts of the tubular drive transmission, a passage 149 isprovided in the boss 136. The passage opens at one end 149a incommunication with the central opening 142 of the boss and at the otherend 149b at the exterior of the housing, and is inclined downwardly andoutwardly. The open end 149a is located just above the restricting flatsides 148, opening into a wider section of the central opening 142 wherewater, leaking along the antenna mast, can be intercepted beforereacting the drive elements and carried away through the lessrestrictive passage 149 to the outside of the housing.

The housing piece 126 has an opening 150 in the top wall 138, in which abearing 151 is located that rotationally supports a shaft 152 of a motorarmature 154, the axis of which is parallel to the longitudinal extentof the antenna mast 115.

The housing piece 130 is a generally cylindrical, cup-like, member thatcarries a bearing 156 at an upper end, in which the armature shaft 152is journalled. It also carries permanent field magnets 158 and brushes159, thereby forming, together with the armature, an electric motor 160of compact dimensions.

The drive transmission 134 has a drive pulley 161 in the cavity 131,secured to the end of the motor shaft 152, which extends through the topwall 138 into the cavity 131. A driven pulley 162 is supported laterallyto one side of the drive pulley 161, between two retaining flanges 164,166 above and below the driven pulley. The upper flange 164 is part of anut 168 with internal threads 170 that engage with the threads of thecord 146. The nut 168 has a elongated tubular body 168a journalled forrotation at upper and lower ends in bearings 172, 174. The bearing 172is secured in the housing piece 126 and the bearing 174 in the housingpiece 128, each adjacent a respective boss 136, 140, mounting the nut inaxial alignment with the central openings 142, 144 that together form athrough passage. The lower flange 166 that retains the driven pulley 162encircles the body portion 168a of the nut. A spring 176 is interposedbetween and connected to both the driven pulley 162 and the nut 168, sothat rotation from the driven pulley to the nut is transmitted throughthe spring 176. The spring shown is a coil spring secured to the pulleyand nut by insertion of bent ends into apertures of radially opposedsurfaces, but could alternatively be an energy absorbing mechanism indifferent form. The threaded relationship of the nut 168 and the cord146 results in the longitudinal movement of the cord 146 upon rotationof the nut 168, which is restrained from axial movement by the bearings172, 174. Thus, rotation of the nut through the transmission 174 drivesthe cord in a direction to extend the antenna sections or retract them,depending upon the direction of motor rotation. Because the pulley 161is substantially smaller in diameter than the pulley 162, a speedreduction and power increase results. Rotation of the pulley 161 istransmitted to the pulley 162 through a timing belt 178.

As shown in FIG. 9, the upper boss 136 receives the supporting tube 114in closely surrounding relation. A large central passage portion 142a atthe outer end of the boss receives the lower portion of the antenna mast115. The mast is secured to and supported by a base connector 180 havinga threaded end 180a received in a threaded portion 142b of the centralopening 142. The base connector 180 has a central opening 182 throughwhich the cord 146 extends. It will be understood that, in the normalmanner, the cord 146 is secured to the upper end section of thetelescoping antenna, thereby extending and retracting all all of thesections when driven relative to the housing.

The central opening 144 of the boss 140 receives a tube nipple 182 towhich the tube 122 is secured. The tube extends upward into the opening144. A shoulder 182a on the nipple retains it within the housing. Thestorage tube 122, being flexible, can be bent to whatever contourdesired, depending upon the wheel well shape and construction in whichthe assembly is mounted, to provide an enclosure for the cord 146 whenthe antenna mast is collapsed.

As an alternative to the spring 176 for transmitting rotation betweenthe driven pulley 162 and the nut 168, an overrunning clutch as shown inFIGS. 10 and 11 can be used between the two parts. The preferredconstruction automatically decreases the force by which the nut anddriven pulley are interengaged when the antenna reaches the end of itstravel during extension or retraction. Therefore, the clutch overrunssmoothly and without generation of excessive heat. This is accomplishedby the use of a spring strip 184 wrapped in a ring-like shape within aninside cylindrical surface 186 of the driven pulley 162'. The resilienceof the spring strip causes it to engage the inside cylindrical surface186 with sufficient force to frictionally rotate with the driven pulleyunder the loads experienced during extending and retracting the antennasections when the sections are not obstructed. The spring stripencircles the nut 168' and has an inturned flange at 184a, 184b at eachopposite end, received in a common notch 88 in the nut. The notch issufficiently large circumferentially to allow some peripheral movementof the ends of the spring, which are spaced from each other peripherallya short distance, as best illustrated in FIG. 11. As illustrated inFIGS. 10 and 11, the spring surrounds the outside diameter of theadjacent nut portion with radial clearance. Rotation of the pulley,transmitted to the spring through friction, causes rotation of the nutby contact of one of the flanges 184a, 184b of the spring with an end ofthe receiving notch 188. When rotation of the nut is stopped, as at theend of antenna travel, the frictional force of the pulley on the springcauses the spring to rotate slightly. This moves a free end of thespring toward the opposite end, reducing the diameter of the spring andrelieving the frictional force against the inside diameter of the drivenpulley. This allows the driven pulley to be rotated more freely byreduction of the frictional force between the spring and pulley, andthereby reduces the load on the motor and the generation of heat throughthe relative sliding. As will be apparent from FIG. 11., the springfunctions identically in either direction of rotation of the drivenpulley.

An alternate and preferred antenna assembly 210 embodying the inventionis shown in FIGS. 13-15. This embodiment comprises a housing for a motor212 and a drive transmission 213, and a supporting tube 214 forsupporting the assembly and housing a collapsible antenna mast 215comprised of telescoping sections 216a-e. The housing is elongated andvery little wider than the supporting tube 214. The assembly 210 is verycompact and can be mounted within a small space.

As best shown in FIG. 13, the housing is formed of four injection moldedplastic pieces 226, 227, 228, 230, that interfit to form a strongenclosure. Pieces 226, 228 together form a cavity 231 for the drivetransmission 213. The pieces 230, 226 interfit to form a cavity for themotor 212. The housing piece 226 has a cylindrical boss 236 projectingperpendicularly from a top wall coupled to the supporting tube 214through a neoprene rubber coupling 237. The neoprene coupling 237connects the housing to the tube 214 and isolates the housing fromvibration orginating from the mounting surface 55 (FIG. 6) due to roadvibration. The coupling 237 is secured to the housing 212 with a metalband 239 and threaded connectors (not shown). The connectors are screwedthrough holes in the band 239 into the coupling 237, boss 236, astationary antenna section 216e, and finally a plastic insulator 245.

A split sleeve plastic coupling adapter 241 is secured to the supporttube 214 by threaded connectors (not shown) screwed through the tube 214into the adapter 241. A coupling lip 237a engages a slot 241a in theadapter to complete the housing support arrangement. The principalsupport connection between the tube 214 and the housing 212 is throughthe neoprene rubber vibration isolating coupling 237.

The housing piece 228 has a cylindrical boss 240 extending perpendicularto a bottom wall aligned with the boss 236, and accommodating connectionof a flexible storage tube 242 with the housing via a nipple connector243.

Central openings extend through the bosses 236, 240, each axiallyaligned with the other, to accommodate passage of a flexible cord 246through the housing. Beyond the boss 236, the cord is connected to acenter antenna section by a coupling tube 243 crimped around the cord246 and center antenna section 216a. Beyond the boss 240, the cord 246extends into the storage tube 242.

The cord 246 is of plastic, such as Delrin, and is externally threadedon two diametrically opposite portions. The cord has two diametricallyopposite flat outer surfaces 246a, 246b along its length, resulting inperipherally broken threads. The cord passes through a central openingof a tubular plastic insulator 245 within the boss 236. The insulator245 is partially enclosed within the base of the fixed tube 16e and thetwo are positioned around an opening in the housing piece boss 236. Twoopposed flat surfaces 245a, 245b of the plastic insulator 245 preventrotation of the cord 246 relative to the housing, yet provide sufficientclearance to allow free sliding of the cord. Because the inside passageof the insulator 245 is subject to wear from the movement of the cord246 it is made long relative to its diameter and is replaceable withinthe housing.

The drive transmission 213 has a drive pulley 261 secured to the end ofa motor output shaft 252, which extends through a top wall into thecavity 231. A dr.iven pulley 262 is supported laterally to one side ofthe drive pulley 261, between two thrust bearings 272, 274. The bearing272 is supported in the housing piece 226 and the bearing 274 supportedin the housing piece 228.

The driven pulley 262 has a central through passage with internalthreads 270 that engage the threads of the cord 246 and acts as a rotarynut to drive the cord. A timing belt 278 driven by the pulley 261engages the teeth on the pulley 262.

The threaded relationship of the pulley 262 and the cord 246 results inthe longitudinal movement of the cord upon rotation of the hub. Thus,rotation of the hub through the transmission 213 drives the cord in adirection to extend the antenna sections or retract them, depending uponthe direction of motor rotation.

A clutch 284 is interposed between a sleeve 261a and a hub portion 261bof the drive pulley 261 so that rotation from the sleeve to the hub istransmitted through the clutch 284.

The clutch 284 automatically decreases the force by which the hub 261aand sleeve 261b are interengaged when the antenna reaches the end of itstravel during extension or retraction. The clutch overruns smoothly andwithout generation of excessive heat. This is accomplished by the use ofa spring strip wrapped in a ring-like shape within an inside cylindricalsurface of the sleeve 261a. The resilience of the spring strip causes itto engage the inside cylindrical surface with sufficient force tofrictionally rotate with the drive pulley under the loads experiencedduring extending and retracting the antenna sections when the sectionsare not obstructed. Additional details regarding the clutch 284 aredepicted in FIGS. 7 and 8 where a similar clutch is seen forming anintegral part of the driven pulley 62 depicted in those figures.

The FIG. 13 embodiment of the antenna assembly senses antenna travel tocontrol the motor 212. The position of a switch actuator 290 controlsthe status (open or closed) of two switches 292, 293. These switches292, 293 replace the switching circuit 89 of FIG. 4. An open connectionat either contact 292, 293 de-energizes the motor 213.

The actuator position is dictated by a flange 294 connected to thedriven pulley 262 that engages an actuator slot 290a. In the positionshown in FIG. 13, both switches 292, 293 are closed and the motorresponds to switch inputs which cause the antenna to be driven up anddown. When the antenna reaches an end of travel, continued rotation ofthe driven pulley 262 stresses the cord 246 but results in no furtherantenna movement. Instead, wave springs 296, 297 that are biased againstthrust bearing washers 298, 299 flex, allowing the driven pulley 262 andconnected flange 294 to move up or down along the now stationary cord246 as rotation continues.

As the actuator 290 moves up or down, one of two leaf springs 310, 311having ends coupled to the actuator 290 bend. A center support leaf 312that supports a center switch contact 313 remains relatively stationaryduring actuator movement. The actuator 290 defines a shoulder portion290b that engages one or the other of the leafs 310, 311 during actuatormovement and opens one of the switches 292, 293. A movement in theactuator of 105 thousandths of an inch produces a gap of 60 thousandthsof an inch in the affected switch to open circuit the motor 212. Allthree leafs 310-312 are supported by a switch header 314 integrallymolded in the housing piece 228. The leafs 310-312 are metalic and areconnected to the motor 213 and switch SW-1 via conductors 90, 91 so thatan opening of either switch deenergizes the motor.

In an embodiment of the housings 12 and 112 the length L (FIG. 1) is2.84 inches and the height H is 3.75 inches. The width W (FIG. 2) is1.20 inches and the diameter D of the supporting tube 14 is 0.8 inch.Thus, in these embodiment the housing width has been kept to no morethan 1.5 times greater than the width of the supporting tube and thelength no more than 3.6 times greater. The over all height of thehousing and antenna, except for the storage tube 22, 122 with theantenna collapsed, is 12.4 inches. The weight of the preferredembodiment is 15.9 ounces, which is sufficiently light to permitmounting with top hardware (i.e., a bracket or the like at the top ofthe supporting tube 14 or 114) only.

In the preferred embodiment of the antenna housing 212 (FIGS. 13-15) thelength is approximately 3 inches, the height is slightly less that 4inches, the width is approximately 1.5 inches, and the diameter of thesupporting tube 214 is approximately 1.125 inches. For this embodimentthe assembly is also supported only by the supporting tube 214.

The small size of each housing occupies an extremely small volume withina wheel well of the vehicle, which is highly desirable to the automobilemanufacturer. It will be apparent from FIG. 3 that the housingconstruction, the drive transmission construction and arrangement, andthe use of the housing piece 30 as a part of the motor structure, allcombine to provide the extreme compactness and light weight. This iscontributed to by the use of a timing belt 78 and plastic pulley wheels,in lieu of a drive train of gears, which would require additionalelements, supports, and weight.

While preferred embodiments of the invention have been described indetail, various modifications or alterations may be made therein withoutdeparting from the spirit and scope of the invention set forth in theappended claims.

We claim:
 1. A retractable motor-driven antenna comprising a supportingtube, telescoping antenna sections collapsible within the tube, areversible electric motor, transmission means connected between themotor and antenna sections to extend and retract the sections relativeto the tube, a control switch for controlling operation of the motor,and a housing enclosing the motor, switch, and drive means and connectedwith the supporting tube and antenna sections, said motor located andoriented beside the tube, with an armature shaft of the motor parallelwith the tube and antenna sections, said transmission means including adrive belt and first and second speed reducing pulley wheels beneath themotor and antenna sections, the first being on the motor shaft and thesecond supported for rotation in the housing axially aligned with theantenna sections, an internally threaded rotary nut supported forrotation in the housing coaxially with the second pulley, means betweenand interconnecting the nut and second pulley wheel for permittingrelative restrained rotary motion between the nut and second pulleywheel under predetermined load, a flexible cord with external threadportions extending through and threadedly engaged with said nut andconnected to an antenna section, and means stationary with respect tothe housing to prevent rotation of the cord.
 2. An antenna as set forthin claim 1 wherein said means interconnecting the second pulley wheeland nut is a spring interposed between the two.
 3. An antenna as setforth in claim 2 wherein said spring is connected to both the secondpulley wheel and the nut to absorb, store and release rotary energybetween the two.
 4. An antenna as set forth in claim 2 wherein saidspring is positively rotated with and has a lost motion connection toone of said second pulley wheel and nut and frictionally engages theother, the lost motion connection constructed and arranged to reducesaid frictional engagement when one of said second pulley wheel and nutrotates relative to the other.
 5. An antenna as set forth in claim 1wherein said means interconnecting the second pulley wheel and nut is anoverrunning friction clutch.
 6. An antenna as set forth in claim 1, 2,3, 4, or 5 wherein said housing is comprised of first, second and thirdinjection molded plastic pieces, the first and second pieces togetherforming a chamber in which the drive mechanism is housed, the firstpiece having a cylindrical boss extending parallel to the motor armatureand encircled by one end of the supporting tube, and the third pieceforming a housing that in part directly supports the motor armature andsupports motor field poles, said first and second pieces being generallyelongated in the direction between the motor axis and antenna sectionsand narrow in the transverse direction, the width in said transversedirection being no greater than that of said third piece in saidtransverse direction.
 7. An antenna as set forth in claim 6 wherein thesaid width of said first and second pieces is no more than 50% greaterand the length is no more than 3.6 times greater from the diameter ofsaid support tube.
 8. An antenna as set forth in claim 7 wherein thefirst and second pieces each separately journal a portion of the nut forrotation and provide a passage opening through both pieces toaccommodate travel of the cord.
 9. An antenna as set forth in claim 1,2, 3, 4, or 5 wherein said housing has a through passage axially alignedwith the support tube through which the cord passes.
 10. An antenna asset forth in claim 9 wherein said housing has a transverse passage fromsaid through passage adjacent said drive transmission to the exterior ofthe housing.
 11. An antenna as set forth in claim 1, 2, 3, 4, or 5wherein said control switch is bipolar, solid state, and constructed andarranged to remove power from the motor under the application ofpredetermined current and time conditions.
 12. An antenna as set forthin claims 1, 2, 3, 4 or 5 including means to detect movement of saidtransmission and for disabling said motor when said movement stops. 13.An antenna as set forth in claim 1, 2, 3, 4 or 5 wherein said nutcarries a magnet and said control switch is a Hall-effect switch that ismomentarily enabled upon receiving a signal voltage and remains enabledonly as long as the nut is rotated above a predetermined rotationalspeed.
 14. A motor-driven antenna comprising a supporting tube,telescoping antenna sections collapsible within the tube, a reversibleelectric motor, a transmission coupled to the motor including aninternally threaded rotary nut supported for rotation relative to saidtube, means for rotating said nut, and a flexible cord connected to anantenna section and having threaded portions extending through andthreadedly engaging said nut so that rotation of said nut by the motor,which when energized extends or retracts said cord and said antennasections relative to the tube, a housing enclosing the motor andtransmission, means stationary with respect to the housing to preventrotation of the cord as said cord is driven by said nut, and means forsensing rotation of said nut and for disabling said motor once saidrotation stops, said means including a transducer mounted in closeproximity to said nut for generating a sequence of pulses in response torotation of said nut and a switch circuit responsive to said transducerfor terminating energization of said reversible electric motor inresponse to a cessation of said sequence.
 15. The antenna of claim 14wherein said transducer comprises a Hall-effect transducer and saidswitch circuit comprises a switching transistor, rendered conductive bysaid sequence of pulses and having an output coupled to first and secondpower transistors for rendering one or the other of said powertransistors conductive to energize said motor and either extend orretract said antenna sections.
 16. A retractable motor-driven antennacomprising a supporting tube, telescoping antenna sections collapsiblewithin the tube, a reversible electric motor, transmission meansconnected between the motor and antenna sections to extend and retractthe sections relative to the tube, a control switch for controllingoperation of the motor, and a housing enclosing the motor, switch, anddrive means and connected with the supporting tube and antenna sections,said motor located and oriented beside the tube, with an output shaft ofthe motor parallel with the tube and antenna sections, said transmissionmeans including a drive belt and first and second speed reducing pulleywheels beneath the motor and antenna sections, the first being on themotor shaft and the second supported for rotation in the housing axiallyaligned with the antenna sections, an internally threaded rotary nutsupported for rotation in the housing coaxially with the second pulley,means interconnecting the motor shaft and first pulley wheel forpermitting relative restrained rotary motion of the shaft relative thefirst pulley wheel under predetermined load, a flexible cord withexternal thread portions extending through and threadedly engaged withsaid nut and connected to an antenna section, and means stationary withrespect to the housing to prevent rotation of the cord.
 17. An antennaas set forth in claim 16 wherein said means interconnecting the firstpulley wheel and motor shaft is a spring strip clutch interposed betweenthe two.
 18. The antenna set forth in claims 16 or 17 where the housingis comprised of multiple injection molded plastic pieces, a first and asecond of said pieces forming a chamber in which the drive mechanism ishoused, the first piece having a cylindrical boss extending parallel tothe motor output shaft and coaxial with one end of the support tube. 19.The antenna set forth in claims 16 or 17 where the support tube isconnected to the housing by a rubber coupling to isolate the housingfrom vibration transmitted along the support tube.
 20. A motor-drivenantenna comprising a supporting tube, telescoping antenna sectionscollapsible within the tube, a reversible electric motor, a transmissioncoupled to the motor including an internally threaded rotary nut, abearing supporting the nut for rotation relative to said tube, means forrotating said nut, and a flexible cord connected to an antenna sectionand having threaded portions extending through and threadedly engagingsaid nut so that rotation of said nut by the motor, which when energizedextends or retracts said cord and said antenna sections relative to thetube, a housing enclosing the motor and transmission, means stationarywith respect to the housing to prevent rotation of the cord as said cordis driven by said nut, means for flexibly mounting the bearing withinthe housing for limited movement parallel to an axis of nut rotation,and sensing means for sensing when the nut has driven the antennasections to a travel limit by sensing a cessation of flexible cordmovement, said sensing means including an actuator coupled to the nut tosense motion of the nut as continued nut rotation threads the nut alongthe cord, and switching means response to the sensing means fordeactivating the electric motor.
 21. The antenna of claim 20 where thenut includes a flanged portion extending radially outward from an axisof nut rotation and the actuator includes a cam member that engages theflange and follows movement of the flange as the nut threads along thecord.
 22. The antenna of claim 21 where the switching means comprisestwo switch contacts mounted to flexible supports connected to theactuator so that one or the other contact opens in response to movementof the actuator.
 23. A retractable motor-driven antenna comprising asupporting tube, telescoping antenna sections collapsible within thetube, a reversible electric motor, transmission means connected betweenthe motor and antenna sections to extend and retract the sectionsrelative to the tube, a control switch for controlling operation of themotor, and a housing enclosing the motor, switch, and drive means andconnected with the supporting tube and antenna sections, said motorlocated and oriented beside the tube, with an output shaft of the motorparallel with the tube and antenna sections, said transmission meansincluding a drive belt and first and second pulley wheels beneath themotor and antenna sections, an internally threaded rotary nut supportedfor rotation in the housing coaxially with the second pulley, meansinterconnecting the motor shaft and rotary nut for permitting relativerestrained rotary motion of the motor shaft relative the rotary nutunder predetermined load, a flexible cord with external thread portionsextending through and threadedly engaged with said nut and connected toan antenna section, and means stationary with respect to the housing toprevent rotation of the cord.